Field of the Invention
The present invention relates to a liquid developer set.
Description of the Related Art
In a liquid developer (also called wet developer), toner particles can have a small particle size of 2 μm or less as compared with a dry developer. Therefore, the amount of toner particles of the liquid developer attached onto a recording medium can considerably be reduced as compared with the dry developer. In order to still achieve a desired image density with the small amount of attached toner particles, however, the liquid developer has a content of a coloring agent in the toner particles higher than a content of a coloring agent in toner particles of the dry developer.
In the case where the liquid developer is black in color, the content of a coloring agent in the black liquid developer has to be made higher as compared with the contents of coloring agents in liquid developers of other colors, in order to obtain a high-density black image and thereby meet the need of a higher image quality. Accordingly, the content of a coloring agent in toner particles of the black liquid developer tends to be higher. As such a coloring agent for black color, carbon black is commonly used.
Toner particles included in such a liquid developer are produced by means of a granulation method according to which a monomer is granulated while being polymerized by any of a variety of methods, or by means of a pulverization method according to which a polymer is prepared and thereafter pulverized into fine particles. Of these methods, the granulation method using a resin of the core-shell structure for example is known (Japanese Laid-Open Patent Publication No. 2009-096994).